/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/MeshTangents.h
Interpolated tangent and bitangent at barycentric coordinates inside a triangle, for per-triangle computed tangents
void GetInterpolatedTriangleTangent ( int32 TriangleID, const [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & BaryCoords, [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & TangentOut, [UE::Math::TVector](API\Runtime\Core\Math\TVector)< RealType > & BitangentOut ) const